Behavior which helps other members of a species but which diminishes an individual's own chance of reproductive success: Biological altruism can be seen in species with elaborated social organisations like ants, termites, and bees.

The internal time-measuring mechanism which helps adjust an organism's daily activities, seasonal activities, or both, in response to environmental cues: Such biological clocks in a person's body take place in response to age, habits, and the chemical changes that take place in an individual's body.

The use of natural predators, parasites, or disease organisms to reduce the number of pest insects or weed plants: Some insects were chewing up the leaves of Marys favorite plant, so she used a biological control method instead of using a chemical to kill the destructive insects.

The biological mechanisms by which organic matter is relatively rapidly transported from near-surface waters to the deep ocean; such as, through the grazing and defecation of fast-sinking fecal pellets by copepods (defined in this unit) and larger organisms, and the vertical migration of near-surface feeders to mesopelagic depths.